#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include "bits/stdc++.h"
#define int long long
#define endl '\n'
#define Bismillah ios_base::sync_with_stdio(0);cin.tie(0);
#define indexed_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
using namespace std;
using namespace __gnu_pbds;
const int N = 5e5 + 7;
const int INF = 1e18;
const int MOD = 998244353;
int n , a[N] , b[N];
vector < pair < int , int > > v;
signed main()
{
Bismillah;
// freopen("closing.in", "r", stdin);
// freopen("closing.out", "w", stdout);
cin >> n;
for(int i = 1; i <= n; i++)
{
cin >> a[i] >> b[i];
v.push_back({a[i] , b[i]});
}
sort(v.begin() , v.end());
int pref[n];
for(int i = 0; i < n; i++)
{
pref[i] = (i == 0 ? v[i].second : pref[i - 1] + v[i].second);
}
int res = -1;
for(int i = 0; i < n; i++)
{
for(int j = i + 1; j < n; j++)
{
int sum = pref[j] - (i == 0 ? 0 : pref[i - 1]);
res = max(res , (sum - (v[j].first - v[i].first)));
}
}
cout << res << endl;
}
